ABSTRACT
Background:
Lip print analysis, also known as cheiloscopy, is a valuable tool in forensic science for personal identification and sex determination.
Methods:
A total of 116 individuals (58 males and 58 females) were enrolled in this study. Lip prints were obtained using three methods: lipstick application, latent print development, and digital photography. The obtained lip prints were analyzed for accuracy, sex-specific variations, and stability over a 6-month period.
Results:
Lip print patterns exhibited significant differences between males and females across all three methods. The lipstick method demonstrated consistent and identifiable lip print patterns, with 25 males (43.1%) and 39 females (67.2%) displaying pattern 1. In contrast, the latent method showed less consistent results, with lip print pattern 1 observed in 25 males (43.1%) and 28 females (48.3%). Digital photography emerged as a promising alternative, offering detailed documentation capabilities, with pattern 1 observed in 30 males (51.7%) and 37 females (63.8%). However, no statistically significant association was found between lip print patterns and sex in the latent and digital methods. A longitudinal assessment revealed variations in lip print patterns over time, with some individuals showing changes in pattern distribution.
Conclusion:
These findings underscore the utility of lip print analysis in forensic science and emphasize the need for further research to enhance the interpretation of lip print evidence.
KEYWORDS: Cheiloscopy, digital photography, forensic science, latent method, lip print analysis, lipstick method, longitudinal assessment, sex determination, stability
INTRODUCTION
Lip print analysis, also known as cheiloscopy, is a specialized field in forensic science that focuses on the examination and classification of lip prints for personal identification.[1] The unique and individualistic nature of lip prints makes them valuable forensic evidence, particularly in cases where other forms of identification, such as fingerprints or DNA, are unavailable or inconclusive.[2] Lip prints are formed by a unique arrangement of grooves, furrows, and wrinkles on the vermilion border of the lips, and they remain stable throughout an individual’s lifetime.[3]
Although the use of lip prints in forensic investigations dates back several decades, recent advancements in imaging technology and classification systems have enhanced the accuracy and reliability of lip print analysis.[4] Various methods have been employed in lip-print analysis, including the traditional lipstick method, latent print development, and digital photography. Each method offers distinct advantages and challenges, and their comparative accuracy and reliability in forensic applications warrant further investigation.[5,6]
Sex determination is a fundamental aspect of forensic investigation, and lip print analysis has emerged as a potential tool in this regard. Studies have demonstrated sex-specific variations in lip print patterns, with certain patterns being more prevalent in males and females.
MATERIALS AND METHODS
A total of 116 participants from North Bihar, consisting of 58 males and 58 females aged 10–60 years, were enrolled in this study. The inclusion criteria required participants to have no history of lip-related diseases, oral pathologies, or deformities, such as cleft lip or active lesions, and no known allergies to lipstick or cellophane tape. The sample size was determined using G Power software, with calculations based on previous studies, a type I error of 5%, 95% power, and an effect size of 0.678. To account for potential attrition, the sample size was increased by 20%, resulting in a final cohort of 116 participants.
Lip prints were analyzed using the Suzuki and Tsuchihashi classification system, which categorizes lip patterns into six types (type I, I’, II, III, IV, and V). The prints were divided into four quadrants and examined manually under magnification. The study assessed the stability of lip prints over time by recording and analyzing them at baseline and after 6 months. Three techniques were employed to capture the lip prints: the lipstick method, the latent lip print method, and the digital photography method. Each method was designed to ensure accurate and consistent recording of the lip patterns.
Statistical analysis of the collected data was performed using IBM SPSS Statistics software (Version 22.0).
RESULTS
Pattern 1 was observed in 25 males (43.1%) and 39 females (67.2%), totaling 64 individuals (55.2%). Pattern 6 was absent in males but present in three females (5.2%). A Chi-square value of 27.770 (P = 0.000) indicates a significant association between lip print patterns and sex [Table 1].
Table 1.
Distribution of Lip Print Patterns – Lipstick in Males and Females
| Lip Print Pattern - Lipstick | Males | Females | Total | |||
|---|---|---|---|---|---|---|
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|
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| Number | Percentage | Number | Percentage | Number | Percentage | |
| 1 | 25 | 43.1 | 39 | 67.2 | 64 | 55.2 |
| 2 | 2 | 3.4 | 1 | 1.7 | 3 | 2.6 |
| 3 | 22 | 37.9 | 1 | 1.7 | 23 | 19.8 |
| 4 | 6 | 10.3 | 12 | 20.7 | 18 | 15.5 |
| 5 | 3 | 5.2 | 2 | 3.4 | 5 | 4.3 |
| 6 | 0 | 0.0 | 3 | 5.2 | 3 | 2.6 |
| Total | 58 | 100.0 | 58 | 100.0 | 116 | 100.0 |
Chi-square value=27.770; P=0.000: Significant
Pattern 1 was consistent across the lipstick and latent methods (43.1%) but higher in the digital method (51.7%). A significant difference in patterns was found among the methods, with a Chi-square value of 39.007 (P = 0.000) [Table 2].
Table 2.
Comparison of Lip Print Patterns among Lipstick, Latent, and Digital Groups of Males
| Lip Print Pattern | Lipstick | Latent | Digital | |||
|---|---|---|---|---|---|---|
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| Number | Percentage | Number | Percentage | Number | Percentage | |
| 0 | 0 | 0.0 | 13 | 22.4 | 0 | 0.0 |
| 1 | 25 | 43.1 | 25 | 43.1 | 30 | 51.7 |
| 2 | 2 | 3.4 | 0 | 0.0 | 3 | 5.2 |
| 3 | 22 | 37.9 | 8 | 13.8 | 11 | 19.0 |
| 4 | 6 | 10.3 | 7 | 12.1 | 10 | 17.2 |
| 5 | 3 | 5.2 | 5 | 8.6 | 4 | 6.9 |
| 6 | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 |
| Total | 58 | 100 | 58 | 100 | 58 | 100 |
Chi-square value=39.007; P=0.000: Significant
Table 3 compares patterns for females across the three methods. Pattern 1 was most common in the lipstick group (67.2%), followed by the digital (63.8%) and latent (48.3%) methods. Significant differences in patterns were observed, with a Chi-square value of 36.532 (P = 0.000).
Table 3.
Comparison of Lip Print Patterns Among Lipstick, Latent, and Digital Groups of Females
| Lip Print Pattern | Lipstick | Latent | Digital | |||
|---|---|---|---|---|---|---|
|
|
|
|
||||
| Number | Percentage | Number | Percentage | Number | Percentage | |
| 0 | 0 | 0 | 12 | 20.7 | 0 | 0 |
| 1 | 39 | 67.2 | 28 | 48.3 | 37 | 63.8 |
| 2 | 1 | 1.7 | 0 | 0.0 | 2 | 3.4 |
| 3 | 1 | 1.7 | 8 | 13.8 | 6 | 10.3 |
| 4 | 12 | 20.7 | 7 | 12.1 | 7 | 12.1 |
| 5 | 2 | 3.4 | 2 | 3.4 | 3 | 5.2 |
| 6 | 3 | 5.2 | 1 | 1.7 | 3 | 5.2 |
| Total | 58 | 100 | 58 | 100 | 58 | 100 |
Chi-square value=36.532; P=0.000: Significant
DISCUSSION
Lip print analysis, or cheiloscopy, has gained prominence in forensic science due to its potential for personal identification.[1] This study aimed to compare the accuracy of three methods—lipstick, latent, and digital photography—and assess their roles in sex determination and the stability of lip prints over time. The findings revealed that the lipstick method provided consistent and identifiable lip print patterns, with significant differences observed between males and females, making it a reliable tool for forensic applications.[2] In contrast, the latent method showed less consistency, likely due to variations in the quality of the prints, suggesting the need for further refinement.[3] Digital photography emerged as a promising non-invasive method, offering accuracy comparable to the lipstick method and highlighting its potential for standardization in forensic practice.[4]
The study also underscored the importance of lip prints in sex determination, with distinct patterns observed between males and females across the methods. This reinforces the value of lip print analysis as a supplementary tool in forensic investigations, particularly in cases involving unidentified individuals.[5] This study’s longitudinal assessment revealed that while some individuals maintained consistent lip prints over 6 months, others exhibited variations, possibly due to factors such as aging or environmental exposure.[7]
CONCLUSION
In conclusion, this study significantly contributes to the expanding field of lip print analysis in forensic science. Through a meticulous comparison of various lip print methods and a thorough investigation of their efficacy in sex determination, along with an assessment of the stability of lip prints over time, this research offers invaluable insights into the accuracy, reliability, and potential applications of lip prints in forensic investigations.
Conflicts of interest
There are no conflicts of interest.
Funding Statement
Nil.
REFERENCES
- 1.Multani S, Thombre V, Thombre A, Surana P. Assessment of lip print patterns and its use for personal identification among the populations of Rajnandgaon, Chhattisgarh, India. J Int Soc Prev Community Dent. 2014;4:170–4. doi: 10.4103/2231-0762.142018. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 2.Dineshshankar J, Ganapathi N, Yoithapprabhunath TR, Maheswaran T, Kumar MS, Aravindhan R. Lip prints: Role in forensic odontology. J Pharm Bioallied Sci. 2013;5((Suppl 1)):S95–7. doi: 10.4103/0975-7406.113305. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 3.Venkatesh R, David MP. Cheiloscopy: An aid for personal identification. J Forensic Dent Sci. 2011;3:67–70. doi: 10.4103/0975-1475.92147. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 4.Verma Y, Einstein A, Gondhalekar R, Verma AK, George J, Chandra S, et al. A study of lip prints and its reliability as a forensic tool. Natl J Maxillofac Surg. 2015;6:25–30. doi: 10.4103/0975-5950.168227. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 5.Prabhu RV, Dinkar A, Prabhu V. Digital method for lip print analysis: A new approach. J Forensic Dent Sci. 2013;5:96–105. doi: 10.4103/0975-1475.119772. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 6.Abedi M, Afoakwah C, Bonsu DNOM. Lip print enhancement: Review. Forensic Sci Res. 2020;7:24–8. doi: 10.1080/20961790.2020.1751396. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 7.Kapoor N, Badiye A. A study of distribution, sex differences and stability of lip print patterns in an Indian population. Saudi J Biol Sci. 2017;24:1149–54. doi: 10.1016/j.sjbs.2015.01.014. [DOI] [PMC free article] [PubMed] [Google Scholar]